var nm:string = 'csc'
var num:number = 6
var flag:boolean = true
var no:undefined
var null1:null = null
var abc:Array<number> = [1, 2, 3]
var sym:symbol = Symbol('1')
var obj:object = {}
var anyy:any = 1
anyy = '1'
var obj1:{x:number, y:string} = {x:1, y:'1'}
const oneHundred: bigint = BigInt(100);
// let arr3:any = 1
// arr3 = []
// arr3.push(1)


// 更安全
// let arr4:unknown = 1
// arr4 = []
// arr4.push(1)

